Connector formed of insulated wire



Feb. 11, 1969 1. F. MATTHYSSE 3,427,397

CONNECTOR FORMED OF INSULATED WIRE Filed June 23, 1966 FIG.3

INVEN TOR. //W//1/6 M4 777/7551? ATTO/P/VE) United States Patent f 3,427,397 CONNECTOR FORMED OF INSULATED WIRE Irving F. Matthysse, Danbury, Conn., assignor to Burndy Corporation, a corporation of New York Filed June 23, 1966, Ser. No. 559,925 US. Cl. 174-87 2 Claims Int. Cl. H02g /08 This invention relates generally to connectors for joining together the ends of a plurality of electrical conductors, and more particularly to such a connector which is formed of insulated wire.

Pigtails is the term commonly applied to the electrical connections contemplated by this invention. Until now, insulated connectors for pigtail connections have usually been constructed by forming a housing of insulating material about the outer surface of a tubular or conically-shaped socket which includes some form of internal wire-gripping means. Often the gripping means is a. helical screw thread, formed on the inner surface of the socket. In one embodiment illustrated in the prior art, a molded outer housing encloses a conductive wire element which has been wound into a tapered helical shape.

The prior art connectors which rely on inner conductive elements formed of solid or sheet stock generally suffer from a lack of resiliency which restricts buildup and maintenance of effective contact pressure. Conversely, attempts to enhance the resiliency characteristics of such connectors have commonly resulted in devices which are complex, difficult to manufacture and high in overall cost. Attempts to mold wound-wire conductive elements into insulating housings have likewise encountered high costs and difficulties in manufacture due to the necessity for preventing penetration of molten material into the interior of the connector.

Accordingly, the objects of this invention include the provision of an insulated connector which is low in cost, which is relatively simple to manufacture, and which has a minimum of separate parts but is nevertheless characterized by considerable freedom for resilient movement.

Another object is the provision of a method for fabricating such a connector.

A feature of this invention is the use of resilient conductive wire having a substantially conventional circumferential coating of insulation, wherein the wire is formed into a tapered helical configuration, and the coating is selectively removed from the wire to form a body member having a bare conductive inner surface and an insulation covered outer surface.

These and other objects, features, and advantages of this invention will be particularly pointed out and distinctly set forth by the following specification and claims when taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is an elevation view, in section, of an insulated wire form connector and insulation removal tool positioned for use in accordance with this invention;

FIGURE 2 is a partially sectioned elevation view of the wire form connector of FIGURE 1 shown after an insulation removal operation; and,

FIGURE 3 represents a front view of a completed pigtail connection incorporating a connector formed in accordance with this invention.

Referring now more particularly to the drawings, the connector of this invention may be seen to comprise generally a body member 10 formed of insulated conductive spring wire which includes a central wire 12 and an outer jacket 14 of insulating material. The insulated wire is formed into individual turns 13 of decreasing diameter to form a tapered helical coil which defines the body 3,427,397 Patented Feb. 11, 1969 member 10. At the narrow end of the conical shape, an integral handle 16 is formed from the terminal end of the length of wire to provide means for conveniently gripping and rotating the body 10.

After formation of the coiled wire body member 10, selected portions of the insulating jacket 14 may be removed from wire 12 in the interior of the body member to produce exposed metal inner surfaces 18 as shown in FIGURE 2. Removal of the insulation in this manner may be conveniently accomplished by means of a rotating cutter device 20 having cutting blade edges, such as 22, of any suitable design.

With the exposed metal surfaces 18 thus formed, the body member 10 may be twisted onto a pigtail connection of a plurality of insulated conductors 24. The bared ends (not shown) of conductors 24 will then be engaged by the internal exposed conductive surfaces 18 which will effectively contact and interconnect the individual conductors. A completed connection will appear as shown in FIGURE 3, with all external surfaces fully insulated by the jackets 14 and the covering of conductors 24.

To further assure adequate insulation coverage of all external surfaces of the body member 10, the insulation 14- may be allowed to remain undisturbed one one or two coils of wire, such as 26, at the base end 28 of the conically shaped body. An insulated skirt will thus protect the open end of the connector. This feature may be readily achieved by selection and control of cutter 20 and the cutting operation during removal of insulating material 14.

Still further protection against possible inadvertent external exposure of a conductive surface on body 10 can be achieved by positioning the free ends 30, 32 of insulated wire 12 so that they lie within the interior of body 10 as shown in FIGURE 1. Alternatively, free end 30 may be disposed externally of body 10, as shown at 30a in FIG- URE 3 to provide gripping handle means. In such event, the butt end 31 at the tip of free end 30a might be sealed by coating with an appropriate insulation material such as a curable liquid or similar substance to provide adequate insulation protection. To further facilitate gripping and turning of body member 10, handle portion 16 may be formed of a double loop of wire such as is shown in phantom view at 16' in FIGURES 1 and 2, instead of the configuration shown in FIGURE 3.

By shaping and removing insulation from a length of insulated resilient conductive wire in accordance with this description, an insulated pigtail connector which is formed of a unitary piece of material by a simple and inexpensive process, and which is characterized by a capacity for resilient flexure over a wide range of movement to maintain effective contact pressure, may be readily and conveniently fabricated.

This invention has thus been described, but it is desired to be understood that it is not confined to the particular forms or usages shown and described, the same being merely illustrative, and that the invention may be carried out in other ways without departing from the spirit of the invention, and therefore, the right is broadly claimed to employ all equivalent instrumentalities coming Within the scope of the appendant claims, and by means of which objects of this invention are attained and new results accomplished, as it is obvious that the particular embodiments herein shown and described are only some of the many that can be employed to obtain these objects and accomplish these results.

I claim:

1. An article of manufacture suitable for use as an electrical connector, comprising:

a length of resilient conductive wire having a first end portion and a second end portion;

a substantially tubular jacket of electrical insulation material disposed coaxially about said length of resilient conductive wire between said first and second end portions;

said jacket of electrical insulation material being discontinuous about the circumference of said length of resilient conductive wire, forming an exposed uninsulated portion of said resilient conductive wire between the said first and second end portions;

said length of resilient conductive wire and said substantially tubular jacket of electrical insulation material being coiled in a cone-shaped helical arrangement having an apex at the said first end portion and a base at the said second end portion, and having an exterior surface and an interior surface each tapering outwardly away from said apex toward said base;

said jacket of electrical insulation material being positioned to locate said exposed uninsulated portion of said length of said resilient conductive wire on the said inner surface of said cone-shaped helical arrangement;

and a portion of said jacket of insulation material at the said second end portion being continuous about the circumference of said length of resilient conductive wire, forming a fully insulated skirt at the base of said cone-shaped helical arrangement.

2. An article of manufacture in accordance with claim 1, wherein said first end portion of said length of resilient conductive Wire extends outwardly from the exterior surface of said cone-shaped helical arrangement forming a gripping handle, and said jacket of electrical insulation material is continuous about the circumference of said first end portion.

References Cited UNITED STATES PATENTS 3,206,833 9/ 1965 Yonkers 174-87 XR FOREIGN PATENTS 581,997 8/ 1959 Canada.

DARRELL L. CLAY, Primary Examiner.

US. Cl. X.R. 287-; 29-628 

1. AN ARTICLE OF MANUFACTURE SUITABLE FOR USE AS AN ELECTRICAL CONNECTOR, COMPRISING: A LENGTH OF RESILIENT CONDUCTIVE WIRE HAVING A FIRST END PORTION AND A SECOND END PORTION; A SUBSTANTIALLY TUBULAR JACKET OF ELECTRICAL INSULATION MATERIAL DISPOSED COAXIALLY ABOUT SAID LENGTH OF RESILIENT CONDUCTIVE WIRE BETWEEN SAID FIRST AND SECOND END PORTIONS; SAID JACKET OF ELECTRICAL INSULATION MATERIAL BEING DISCONTINUOUS ABOUT THE CIRCUMFERENCE OF SAID LENGTH OF RESILIENT CONDUCTIVE WIRE, FORMING AN EXPOSED UNINSULATED PORTION OF SAID RESILIENT CONDUCTIVE WIRE BETWEEN THE SAID FIRST AND SECOND END PORTIONS; SAID LENGTH OF RESILIENT CONDUCTIVE WIRE AND SAID SUBSTANTIALLY TUBULAR JACKET OF ELECTRICAL INSULATION MATERIAL BEING COILED IN A CONE-SHAPED HELICAL ARRANGEMENT HAVING AN APEX AT THE SAID FIRST END PORTION AND A BASE AT THE SAID SECOND END PORTION, AND HAVING AN EXTERIOR SURFACE AND AN INTERIOR SURFACE EACH TAPERING OUTWARDLY AWAY FROM SAID APEX TOWARD SAID BASE; 